Commercial products such as computer printers, graphics plotters, and facsimile machines have been implemented with ink jet technology for producing printed media. The contributions of Hewlett-Packard Company to ink jet technology are described, for example, in various articles in the Hewlett-Packard Journal, Vol. 36, No. 5 (May 1985); Vol. 39, No. 54 (October 1988); Vol. 43, No. 4 (August 1992); Vol. 43, No. 6 (December 1992); and Vol. 45, No. 1 (February 1994). Example physical arrangements of the orifice plate, ink barrier layer and thin film substructure of printheads are described at page 44 of the Hewlett-Packard Journal of February 1994, cited above, and are also described in U.S. Pat. Nos. 4,719,477 and 5,317,346.
Generally, an ink jet image is formed pursuant to precise placement on a print medium of ink drops emitted by an ink drop generating device known as an ink jet printhead. Typically, an ink jet printhead is supported on a movable print carriage that traverses in linear fashion over the surface of the print medium and is controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller, wherein the timing of the application of the ink drops is intended to correspond to a pattern of pixels of the image being printed.
Typical desktop printers and larger plotters use a rectilinear left and right positioning system to linearly move an ink jet print cartridge or printhead left and right across the surface of a sheet of paper or other printing medium. These printing mechanisms are well suited to scaling upward in size, as demonstrated by desktop printer designs being modified into D & E size plotters.
Although traditional printer system designs have been modified to achieve a certain degree of miniaturization, the nature of and the complexity of rectilinear printing mechanisms pose some drawbacks to miniaturization. Rectilinear motion printing mechanisms typically have motors, gears, cogs, belts, belt-driven or gear assemblies, linear encoders and/or other parts which create motion to drive a printhead left and right across the paper swath. The cost-effectiveness of such assemblies and components decreases with further miniaturization.
Power consumption is a consideration in designing small devices for portable use. Rectilinear print mechanisms, however, limit the portable power efficiency of printing devices. As rectilinear printer designs shrink in size, the printers become less energy efficient due, in part, to the deceleration and acceleration of system components required to reverse direction as the printhead reaches the end of its travel; the shorter the travel, the greater the proportion of the total energy for moving the printhead that is used for reversing directions. The amount of energy consumed is proportional to the mass of the printhead with the associated carriage structure. The gears and belts used in rectilinear printer mechanisms have friction losses. Power consumption due to friction losses on acceleration/deceleration is a major constraint for battery life and initial cost to the customer.